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PubMed2004

Molecular phylogenetics, karyotypic diversity, and partition of the genus Myotis (Chiroptera: Vespertilionidae).

Nucleotide sequences of the mitochondrial cytochrome b gene are reported from bats of the genus Myotis including species of the endemic southern African subgenus Cistugo, Myotis (Cistugo) sebrai and Myotis (Cistugo) lesueuri. We also examined Myotis annectans from Southeast Asia, and Myotis macropus from Australia. The two species of Cistugo and Myotis annectans represent the only species of Myotis to differ in chromosome number from the common 2n=44 found in >40 species. Our results show that the two species of Cistugo are more divergent from the other species of Myotis than several other well-recognized genera and we recommend elevating Cistugo to full generic rank. Myotis annectans groups well within Myotis, clustering with other Southeast Asian and Japanese species, and thus represents the only species of Myotis known to have diverged from the common 2n=44 karyotype. Myotis macropus clusters within a clade that includes Southeast Asian species.

Animals↗
PubMed2001

XX:XY sex chromosome system with X heterochromatinization: an early stage of sex chromosome differentiation in the Neotropic electric eel Eigenmannia virescens.

An early stage of sex chromosome differentiation is reported to occur in the electric eel Eigenmannia virescens (Pisces, Sternopygidae) from populations of two tributaries of the Paraná river system (Brazil). Cytogenetic studies carried out in the two populations showed that the Mogi-Guaçu population is characterized by 2n = 38 chromosomes and undifferentiated sex chromosomes and the Tietê population presents 2n = 38 both for males and females and an XX:XY sex chromosome system. The X-chromosome is acrocentric, easily recognized by the presence of a conspicuous heterochromatin block in its distal portion; the Y-chromosome is probably one of the medium sized acrocentrics present in the male karyotype. BrdU induced R-bands of the two populations did not reveal any difference in the euchromatic regions of the chromosomes. AluI and HaeIII restriction enzyme digestion patterns and chromomycin A3 staining of the X-chromosome are presented. The possible role of heterochromatinization in the evolution of sex chromosomes in fish is discussed.

Animals↗
PubMed2001

Representational difference analysis reveals genomic differences between Q. robur and Q. suber: implications for the study of genome evolution in the genus Quercus.

Very similar genome sizes, similar karyotypes and heterochromatin organisation, and identical number/position of ribosomal loci characterise the common oak (Q. robur) and the cork oak (Q. suber), two distantly related oak species. Representational Difference Analysis (RDA) was used to subtract the genome of Q. suber from the genome of Q. robur in order to search for genome differentiation. A library of 400 clones (bearing RDA fragments) representing genome differences between the two species was obtained. Seven Q. robur-specific DNA sequences were analysed with respect to their molecular and chromosome organisation. All belong to the dispersed repetitive component of the genome, as revealed by Southern hybridisation and in situ hybridisation. They are present in the Q. robur genome in between 100 and 700 copies, and are distributed along the length of almost all chromosomes. A search for homologies between RDA fragments and sequences in Genbank revealed similarities of all RDA fragments with known retrotransposons. The RDA fragments were also tested for their presence/absence in the genomes of six additional oak species belonging to different phylogenetic groups, in order to examine the evolutionary dynamics of these DNA sequences.

Base Sequence↗
PubMed1987

A comparative chromosome banding analysis of the Ursidae and their relationship to other carnivores.

Trypsin G-banded karyotypes of eight species of Ursidae were prepared from retrovirus-transformed skin fibroblast cultures. The banding patterns of all bears are highly conserved, even though their diploid numbers range from 42 to 72. A comprehensive analysis of the homologous banding patterns within the Ursidae and with a hypothesized ancestral carnivore karyotype permitted the reconstruction of three significant chromosomal reorganization events that occurred during the evolution of the modern ursids. The first was a multichromosomal fissioning away from the biarmed (2n = 44) primitive carnivore karyotype, leading to six species of the Ursinae subfamily (2n = 78). The second was a comprehensive chromosome fusion in the lineage that led to the Ailuropodinae (giant panda) subfamily (2n = 44). The third event was a second, independent, but less extensive, centromeric fusion occurring in the line that led to the Tremarctinae (spectacled bear) subfamily (2n = 52). Ursidae karyotypes are not only highly conserved within the family but also exhibit extensive chromosome banding homology with other carnivore families.

Animals↗
PubMed1999

Reciprocal chromosome painting shows that genomic rearrangement between rat and mouse proceeds ten times faster than between humans and cats.

Reciprocal chromosome painting between mouse and rat using complete chromosome probe sets of both species permitted us to assign the chromosomal homology between these rodents. The comparative gene mapping data and chromosome painting have a better than 90% correspondence. The reciprocal painting results graphically show that mouse and rat have strikingly different karyotypes. At least 14 translocations have occurred in the 10-20 million years of evolution that separates these two species. The evolutionary rate of chromosome translocations between these two rodents appears to be up to 10 times greater than that found between humans and cats, or between humans and chimpanzees, where over the last 5-6 million years just one translocation has occurred. Outgroup comparison shows that the mouse genome has incorporated at least three times the amount of interchromosomal rearrangements compared to the rat genome. The utility of chromosome painting was also illustrated by the assignment of two new chromosome homologies between rat and mouse unsuspected by gene mapping: between mouse 11 and rat 20 and between mouse 17 and rat 6. We conclude that reciprocal chromosome painting is a powerful method, which can be used with confidence to chart the genome and predict the chromosome location of genes. Reciprocal painting combined with gene mapping data will allow the construction of large-scale comparative chromosome maps between placental mammals and perhaps other animals.

Animals↗
PubMed1989

[Study on karyotypes C-banding and Ag-NORs of Rana minimus and Hyla chinensis from Fuzhou].

Using bone marrow preparing chromosome method, BSG technique and a quick Ag-stained NORs method, the conventional, C-banded and Ag-stained karyotypes of Rana minimus Ting et Ts'ai and Hyla chinensis Guenther were studied. The diploid number of R. minimus is 2n = 26, consisting of 5 pairs of large and 8 pairs of small chromosomes. A secondary constriction is observed at a position near the centromere on the short arm of chromosome No. 6 and it is also the position of the "standard NORs" Chromosome C-banding shows that the heterochromations of R. minimus are located in the centromeric and pericentromeric regions, with comparatively few lightly-stained interstitial C-bands and no telomeric ones. And the secondary constriction is C-banding positively stained. H. chinensis has 24 chromosomes which divide into a group of 6 large pairs and a group of 6 small pairs. A secondary constriction appears at a position on the long arm of chromosome No. 10. It is also the position of the "standard NORs" and C-banding positively stained. The C-banding pattern is mainly composed of centromeric C-bands with few interstitial ones and no telomeric ones. The karyotypic characters of Ranidae and Hylidae and the relationship to the evolution are also discussed.

Animals↗
PubMed1988

Tetraploidy (92,XXYY) in an acute nonlymphocytic leukemia (M1) patient following autologous bone marrow transplantation.

Tetraploidy (4n = 92) without structural chromosome aberrations was found in bone marrow cells of a patient with acute nonlymphocytic leukemia, FAB classification M1, following autologous bone marrow transplantation. This finding, which remained undetected during the remission phases and appeared at relapses, progressed to a hypotetraploid modal number (74 chromosomes) at the terminal phase of the disease. Together with two previous observations in patients with acute lymphoblastic leukemia with L2 morphology and a null cell immunotype, this observation supports the hypothesis that tetraploid karyotypes may represent unusual and aspecific patterns of clonal evolution.

Adult↗
PubMed1978

Conservation and chromosomal localization of DNA satellites in balenopterid whales.

DNA satellites were isolated from three balenopterid species, viz. the minke, sei, and fine whales. In each of them at least two DNA satellites were recognizable with buoyant densities in neutral CsCl of rho = 1.702/1.703 and rho = 1.710/1;711, respectively. cRNAs from each satellite group were used for filter and in situ hybridisations. Homo-and heterologous DNA-cRNA hybrids within each satellite group yielded virtually identical melting curve profiles showing conservation of at least a considerable part of the DNA satellite sequences. There was no evident sequence homology between the rho = 1.702/1.703 and the rho = 1.710/1;711 satellites by filter hybridisation.--The in situ hybridisation showed that in each species the rho = 1.702/1.703 satellite was located in centromeric-paracentromeric C-bands in a few pairs, whereas the rho = 1.710/1.711 satellite was located in terminal C-bands throughout the karyotypes.--The data on the whale DNA satellites indicate that the quantitative evolution of the sateliite DNA sequences preceded species divergence of the balenopterids and that the satellite sequences have remained relatively unaltered since the divergence took place. The function of satellite DNA is considered to imply the introduction of both chromosomal and genic polymorphisms and thus being of great importance in speciation, Based upon these concepts a model is postulated for the function of satellite DNA. According to this model at meiotic pairing euchromatinheterochromatin overlapping between homologous chromosomes is considered to be of a general occurrence. This overlapping is presumed to be accentuated by the size heteromorphism frequently observed between homologous heterochromatic segments (C-bands). In the region of such euchromatinheterochromatin overlapping, cross-over would be excluded. The overlapping is suggested to be rectified progresssively in the chromosome arms, leaving unaffected crossing-over distant to the euchromatin-heterochromatin junctions. The consequence of this will be that genes in the proximity of the junctions are collectively inherited and selected, whereas genes distant to the the heterochromatin will be independently assorted and selected.

Animals↗
PubMed1976

A comparative analysis of the karyotypes of Cricetus cricetus and Cricetulus griseus.

This study presents a comparison of the mitotic chromosomes of the two species of hamsters Cricetus cricetus (European hamster) and Cricetulus griseus (Chinese hamster), which have the same chromosome number of 2n=22.--G-banding procedure reveals striking similarities in both karyotypes and gives the possibility to analyse structural changes so that two examples for Robertsonian rearrangement can be observed.--A remarkable kind of difference between the two karyotypes becomes obvious after C-banding procedure. While Cricetus cricetus shows a large amount of predominantly centromeric heterochromatin, in Cricetulus griseus C-bands are less conspicuous, and a few chromosomes do not exhibit any centromeric heterochromatin at all.

Animals↗
PubMed1983

[Clinical evolution and cytogenetic study of two acute lymphoblastic leukemia (type L2) in the child: prognostic value of the karyotype].

Cases of two newborns with acute lymphoblastic leukemia (ALL) L2 type, are reported. In each case, some chromosomal abnormalities can be found. In the first case, a translocation t (4;11) is noticed. It has to be compared with already published patients' cases and so the non randomly occuring character of those alterations in ALL and poor pronostic factor can be confirmed. In the second observation, a complex translocation t (5;6;X) never described before in literature, was observed. Chromosomal findings in ALL are not only a help to diagnosis but, by cytogenetic data, are also a help to accurate prognosis and adequate treatment.

Age Factors↗
PubMed1978

Chromosomal evolution in Malagasy lemurs. III. Chromosome banding studies in the genus Hapalemur and the species Lemur catta.

The karyotypes of five Malagasy lemurs are described and compared after the successive use of various banding methods. Phylogenic relationships appear to exist between the respective ancestors of Lemur catta, Hapalemur simus, H. griseus occidentalis, H. griseus ssp, and H. griseus griseus. Their karyotypes can be derived from that of L. fulvus fulvus by chromosomal rearrangements affecting mainly chromosomes 1 and X. Intense staining of juxtacentromeric heterochromatin was detected among the different subspecies of H. griseus.

Animals↗
PubMed1982

Chromosomal evolution in "lemurs". VI. Chromosomal banding studies of Galago senegalensis, Galago alleni, Galago demidovii and Euoticus elegantulus.

The karyotype of four Galagidae (Galago senegalensis, G. demidovii, G. alleni and Euoticus elegantulus) are studied and compared with the aid of various banding techniques. Many common chromosome segments were found, and it was possible to reconstruct a hypothetical ancestral karyotype for the family. It was also possible to show the relation between the chromosomes of Galagidae with those of two Lorisidae. The general scheme of chromosomal evolution of the Lorisiforms can be proposed, resulting from a common populational evolution followed by an accumulation of translocations, mostly of the Robertsonian type. Several pericentric inversions have also occurred in the trunk of the Lorisidae, emerging from this common population. Then, Galagidae have evolved, each species independently, by an accumulation of translocations, mostly Robertsonian, whereas Lorisidae have accumulated pericentric inversions prior diverging.

Animals↗
PubMed2004

Multicolor FISH mapping of the dioecious model plant, Silene latifolia.

Silene latifolia is a key plant model in the study of sex determination and sex chromosome evolution. Current studies have been based on genetic mapping of the sequences linked to sex chromosomes with analysis of their characters and relative positions on the X and Y chromosomes. Until recently, very few DNA sequences have been physically mapped to the sex chromosomes of S. latifolia. We have carried out multicolor fluorescent in situ hybridization (FISH) analysis of S. latifolia chromosomes based on the presence and intensity of FISH signals on individual chromosomes. We have generated new markers by constructing and screening a sample bacterial artificial chromosome (BAC) library for appropriate FISH probes. Five newly isolated BAC clones yielded discrete signals on the chromosomes: two were specific for one autosome pair and three hybridized preferentially to the sex chromosomes. We present the FISH hybridization patterns of these five BAC inserts together with previously described repetitive sequences (X-43.1, 25S rDNA and 5S rDNA) and use them to analyze the S. latifolia karyotype. The autosomes of S. latifolia are difficult to distinguish based on their relative arm lengths. Using one BAC insert and the three repetitive sequences, we have constructed a standard FISH karyotype that can be used to distinguish all autosome pairs. We also analyze the hybridization patterns of these sequences on the sex chromosomes and discuss the utility of the karyotype mapping strategy presented to study sex chromosome evolution and Y chromosome degeneration.

Blotting, Southern↗
PubMed2001

Phylogenetic implications of the 38 putative ancestral chromosome segments for four canid species.

Chromosome homologies between the Japanese raccoon dog (Nectereutes procyonoides viverrinus, 2n = 39 + 2-4 B chromosomes) and domestic dog (Canis familiaris, 2n = 78) have been established by hybridizing a complete set of canine paint probes onto high-resolution G-banded chromosomes of the raccoon dog. Dog chromosomes 1, 13, and 19 each correspond to two raccoon dog chromosome segments, while the remaining 35 dog autosomes each correspond to a single segment. In total, 38 dog autosome paints revealed 41 conserved segments in the raccoon dog. The use of dog painting probes has enabled integration of the raccoon dog chromosomes into the previously established comparative map for the domestic dog, Arctic fox (Alopex lagopus), and red fox (Vulpes vulpes). Extensive chromosome arm homologies were found among chromosomes of the red fox, Arctic fox, and raccoon dog. Contradicting previous findings, our results show that the raccoon dog does not share a single biarmed autosome in common with the Arctic fox, red fox, or domestic cat. Comparative analysis of the distribution patterns of conserved chromosome segments revealed by dog paints in the genomes of the canids, cats, and human reveals 38 ancestral autosome segments. These segments could represent the ancestral chromosome arms in the karyotype of the most recent ancestor of the Canidae family, which we suggest could have had a low diploid number, based on comparisons with outgroup species.

Animals↗
PubMedDate not supplied

Leukemic transformation in patients with 5Q- and additional abnormalities.

BACKGROUND AND METHODS: We analyze myelodysplastic patients with the 5q- marker as sole abnormality, or with additional anomalies, and their relationship to clinical evolution. The study was performed on 12 patients (6 females and 6 males): 3 with refractory anemia (RA), 5 with RA with ring sideroblasts (RA-S), 3 RA with excess of blasts (RAEB) and 1 with RAEB in transformation (RAEB-T). The cytogenetic study was carried out on bone marrow cells at the time of diagnosis. The G- banding technique was used for chromosome identification. The follow-up was for 50 months. RESULTS AND CONCLUSIONS: Five patients (3 with RA and 2 with RA-S) showed a single 5q- marker. They had a long survival without evolution to leukemia. All cases with 5q- plus additional abnormalities: del(12p), del(7q), del(14q), i(11q) and i(17q), showed a neoplastic evolution in a short period of time. We can conclude that the presence of the 5q- marker with complex karyotypes or additional abnormalities is associated with a high risk of neoplastic evolution, indicating the prognostic value of cytogenetic study in myelodysplasia.

Aged↗
PubMed2001

Chromosome evolution in the annual killifish genus Cynolebias and mitochondrial phylogenetic analysis.

Extensive chromosome variation involving Robertsonian and non-Robertsonian changes were proposed to explain chromosomal evolution within killifishes of the aplocheiloid group belonging to the order Cyprinodontiforms. In the present work we describe the karyotypes of four Cynolebias species and analyze chromosome changes by means of mitochondrial phylogenetic studies, including 10 taxa of this genus. Diploid numbers varied from 48 to 44 and the number of chromosome arms from 50 to 54. Molecular phylogenetic analyses allow us to corroborate previous hypothesis about chromosome evolution in aplocheiloid fishes. The tree topology based on a combined dataset of mitochondrial cytochrome b and 12S genes shows that recent cladogenetic events within the genus Cynolebias could have occurred by allopatric or 'in-situ' differentiation involving chromosomal rearrangements. Our analyses of approximately 10% of mitochondrial genome can be helpful in determining these recent cladogenetic events but it showed limited phylogenetic resolution at intermediate levels of divergence. This can be explained in part by the high levels of DNA sequence divergence (ranging from 0.015 to 0.245) detected at intrageneric level. Different methodological approaches suggest that chromosomal changes in Cynolebias have occurred during their differentiation, supporting the hypothesis that the unresolved basal polytomy could be the result of rapid speciation events, like a true 'star polytomy'.

Animals↗